Did you know that one laboratory fume hood uses as much energy in a year, as three average U.S. homes combined? Approximately 60% of laboratory energy bills go to HVAC systems that need to compensate for fume hoods. Improvements to fume hoods represent a gigantic, green potential for cost savings in laboratory sustainability initiatives. This blog post is meant to explain how to get the best return on investment for a fume hood upgrade in your specific laboratory setting.
High energy consumption by Constant Air Volume fume hoods (CAV)
For background...traditional constant air volume fume hoods were originally designed with a singular goal - to keep us safe while working with hazardous chemicals. CAV fume hoods provide a safe working environment by constantly drawing air out of the work space and expelling it outside through a lab building's centralized ducting system. This process places a heavy load on lab HVAC systems. An exorbitant amount of energy is used to constantly re-supply the lab with heated or cooled, room temperature air. All while the hood is actually in use or not...
High efficiency design of Variable Air Volume (VAV) fume hoods
Today's high efficiency VAV fume hoods are optimized for safety and energy consumption. Their improved aerodynamic design allows for safer containment at much lower airflow speeds. They often have advanced control systems for varying airflow volumes with occupancy sensors. High efficiency fume hoods truly are better performers and better for the environment.
However, unless you are planning a new building, replacing all the fume hoods in your laboratory isn't prudent. VAV have high price tags. The hassle of removal and re-installment translates into work time lost. Environmentally responsible disposal of your current hood is an issue. The pay back time on the investment may not make sense.
Retro fit kits are a great way to implement the VAV design attributes into your fume hood. These kits are 10-20% of the cost of a new hood. They can be quickly installed in less than four hours. The pay back period is projected at around two years. Your current fume hood can become as safe and as green as a new VAV.
Actual fume hood retrofit kit energy efficiency results depend on how much 'internal heat' your laboratory generates
The key is to get an accurate estimate of what the energy cost savings will be given how your particular laboratory currently operates. The actual savings outcome can vary from 75% to 10% in the context of your laboratory environment. This is because cooling the laboratory air places the most wasted energy demand on HVAC systems.
Surprisingly, in cases where your laboratory is being significantly heated by your lighting system,laboratory equipment, or even direct sunlight – the fume hood constantly running helps to remove all that excess heat. A VAV hood might even increase your energy bills. Weird, right? This doesn't mean you can't reduce your lab's energy consumption. The situation only requires a good overall plan.
The highest potential energy savings result from installing a retro fit kit to your fume hood and concurrently reducing sources of 'internal heat' gains in your lab.
Reach up to 75% energy savings for your laboratory HVAC system
Your best outcome with a retrofit fume hood, will result by implementing these “internal heat gain” green lab tips.
1.Change laboratory lighting to LED
2. Automate lighting with occupant sensors..
3. Set controlled lighting schedules.
3. Use window shades or blinds to block or utilize solar heat gains.
4. Move heat releasing laboratory equipment (i.e. ULT freezers) into cooler, window-less rooms, optimally in rooms with local HVAC zone recirculation.
5. Check with the energy provider utility company for rebates
The overall effort is worthwhile, because the pay back includes a future where funding is reserved for scientific research - rather than HVAC energy waste!
For further reading...
1. Retrofit hoods to improve safety, reduce energy use (2013) Lab Designs News
2. Impact of Fume Hood Retrofits on the Energy Performance of Laboratory Spaces. Report to NEMIC National Energy Management Institute Committee by Myers-Lawson School of Construction at Virginia Tech Department of Building Construction Department of Mechanical Engineering. September 2014